Know THIS Python List Tip!!

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In this short, I explain how to use the index method, the pop method, and the insert method to remove an item from a list and place it at the front of the list.
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[@petrlaskevic1948]

It would be so much better to store an int with the index of the used item, and use that instead of shuffling the array around.

[@gregcarlson8438]

This is what I was thinking

[@houmy9041]

You mean like an enum

[@cctz_1]

Can you explain a little bit please ? Sorry im new to coding and want to understand

[@petrlaskevic1948]

@@cctz_1 Learn how to use arrays/lists

[@Lllllluuj]

@@cctz_1 basically he is saying that you can enumerate the list, which allows for the items to have a number associated with it (index) and you can just use the indexed number with the sword to call it, instead of having to move sword to 0

[@shiinondogewalker2809]

I'm just thinking why you'd want the items to move around on the hotbar instead of highlighting which is selected

[@MsWhiskey974]

Then if you add or remove an item from the hotbar, you will also need to offset the list cursor used for highlighting. This can be avoided if list has fixed size and stores empty slots somehow. Again, I guess there are lots of ways to achieve a hotbar, some saner than others xD

[@shiinondogewalker2809]

@@MsWhiskey974 right, I'd think an array for the hotbar plus an int which specifies which is selected would be a good approach

[@MsWhiskey974]

@@shiinondogewalker2809 I’d probably go with that as well. That way, you can have empty slots which is pretty common for game hotbars and items won’t move around which is less error prone.

[@fishingmasterxy]

hashmap that stores linked nodes would work for frequent switching of items if you use the item name as the key. and have a reference to the head of the list. constant time operations. for switching and finding the value

[@erinmutchler3612]

Yeah I was gonna say. Isn’t insert() linear time? I feel like a linked list would be much better. Or heck, even a growable array and then use the last element of the array as the item in the players hand

[@fishingmasterxy]

@@erinmutchler3612 yeah, hashmap for finding the value to switch, the value being a linked node. constant time to find the item, constant time to do the switch

[@arielguzman2875]

This should be the preferred method to be efficient. Likely rethink the need for a list for this op.

[@mattmurphy7030]

A hash map for 10 items is next level stupid first year coder mistake

[@fishingmasterxy]

@@mattmurphy7030 For small inputs yeah. I was giving theoretical O(N) for the algo for any size N

[@phantompayne8248]

The bgm is soo good!!

[@troybaxter]

You can continue this logic further and request the items you want to swap. Just add these lines: try: temphb = list(map(str.lower, hotbar) item = input(“Item 1: “) index1 = temphb.index(item) try: swapItem = input(“Item 2: “) index2 = temphb.index(swapItem) hotbar[index1], hotbar[index2] = hotbar[index2], hotbar[index1] print(hotbar) except: print(“Item Doesn’t in Hotbar to Swap With”) except: print(“That item isn’t in your hotbar”) Throw in a couple try-except lines, a while loop, and you have a fully functioning hotbar swapping program

[@troybaxter]

@Man Aquatic where did I make a mistake? I’ll edit it if needed.

[@yungmaz13]

@@troybaxter I think Man Aquatic is confused because of the indentation

[@troybaxter]

@@yungmaz13 yeah, blame KZbin on that.

[@yungmaz13]

@@troybaxter Lmao, you could use spaces to indent

[@troybaxter]

@@yungmaz13 the problem is that it is weird on the phone or on notifications.

[@POWERSID17]

You should make a playlist of full python course. ❤

[@alexhernandez8550]

Would recommend also using a json to structure your game inventory

[@eyebol]

do you mean a dictionary?

[@Hex-Scholar]

list = ["sword", "bow", "axe"] list[list.index("axe")], list[0] = list[0], list[list.index("axe")]

[@epsi]

Slightly inefficient due to calling list.index twice. If using Python 3.8 or newer, you can abuse the walrus operator: list[i], list[0] = list[0], list[(i := list.index("axe"))] I call it abuse because it's not exactly intuitive. For example, this alternative attempt is incorrect: list[(i := list.index("axe"))], list[0] = list[0], list[i]

[@Hex-Scholar]

@@epsi Thanks, yes the complexity of my code will be 2*n, in the worst-case, to keep it n, I could first find the index and store it inside a variable and then go for the swap, but what is the fun in that 😅 As for the walrus operator, I have studied about it, but not really used it that often. Also, I was trying to do this too: list[(i := list.index("axe"))], list[0] = list[0], list[i] Apparently it doesn't work :(

[@mousepotatoliteratureclub]

@@epsi True, but if your list is long enough/your items complex enough for this to cause performance issues, you should be using something more efficient than O(n) index lookup anyway.

[@epsi]

@@mousepotatoliteratureclub Definitely agree. Just wanted to point out the walrus operator's utility here to reduce the time complexity of a "simple" assignment from O(2n) to O(n).

[@Евгений-р7р3ф]

@@Hex-Scholar, It happens because of the time of compiling pieces of your code. In case of assigning operator it works left-to-right order. The right-to-left compiling string of the code must not exist since your should evaluate the data which you're assigning to the variable first and then assign that.

[@Tripicality]

Helpful video, but those flickering green subtitles are very uncomfortable to look at

[@b001]

I agree. I wanted to try it out, but I dont think they work well with my shorts. You can’t read subtitles and look at code at the same time. Likely won’t add them again. Thanks for the feedback!

[@samuelpacheco1222]

A O(1) solution: Transform every item to a constant number (enumerated enums) Torch = 1 Rock = 2 Potion = 3 Sword = 4 Shield = 5 And create an unordered_map of pointers such as a[index] = index So we know that for a[1] = 1 and that means a[torch] = 1 // torch is in slot 1! Swaps become constants Sword = 4 Torch = 1 a[1] = a[4] // first bucket nows points to index 4 This is the same as a[torch] = a[sword] // torch now it’s wherever sword currently is Then lastly a[4] = 1 a[sword] = 1 // this is telling sword points to position 1 Memory is O(N) (you only need the pointers array) Swaps O(1) As en excercise: how to reconstruct the array in order from the pointer array in O(N)?

[@sebastiangudino9377]

This is the correct solution. In thid contects the values of the enum are an ID. This is a very common pattern in games where you have a lookup table of all items. And you just work with the ID's instead (Never copying, never moving, basicaly pointers)

[@mattmurphy7030]

Using a map for 10 items is the dumbest solution you could have come up with

[@pandalonium]

I genuinely thought you were going to show how you can do all of that in one line

[@edizdogankarakoc7768]

Wouldn't it be more compact if we connected 8th and 9th line by typing: hotbar.remove("Sword") hotbar.insert(0, "Sword") print(hotbar) ------------------------------------------------ Please correct me if I'm wrong.

[@panosmpasiourasserrano7449]

You might have multiple swords in your hotbar

[@ferretdevshit2838]

for my fellow one line freaks: hotbar = [x for x in ["Sword",*hotbar] if x != "Sword"] effiency depends on the amount of items in the inventory, would be faster if the list if small but much less efficient if ur user can have like 5 billion items as its still a for loop apart from that, the same functionality can also be one-lined easily as the pop method returns the item, giving us hotbar.insert(0, hotbar.pop("Sword"))

[@juhotuho10]

cool tutorial, but oh man is that a terrible way to implement a hotbar

[@imvine]

Wait Wait wait it just moves the list instead of overwriting Torch Is that what pop does?

[@lillii9119]

That's the "insert". list.insert(0, x) will shift all items before inserting in index 0. If you want to overwrite you need list[0] = x

[@Loading_Code]

Wow bro❤

[@ScienceWorldz]

We can combine all those lines into..... hotbar.insert(0, hotbar.pop(hotbar.index("Sword")))

[@clipstobingeon]

❤❤❤❤

[@ehudkotegaro]

Both pop and insert are potentially pretty expensive. Can't you just l[index],l[0]=l[0],l[insert]?

[@mohammedvaseem3331]

Theme?

[@massy-3961]

O(3N) solution lmfao

[@raymondarrington5339]

O(N)

[@HowaboutNope-uh2yx]

Bro, first of all you don't know how big O notation works, second, you can't solve this problem faster than O(N).

[@BlueSky-fj7yi]

Thats not how it works 😨

[@massy-3961]

@@HowaboutNope-uh2yx just because you can’t solve it better than O(N) doesn’t mean you should take O(3N) solution when it could legitimately be O(1N), not to mention you most certainly can if you use the right data structure for the task, which an array is most certainly not the right data structure for making modifications on the front. Not to mention you can actually do this better than O(N) on average with worse case being O(N) even with an array.

[@FlorianWendelborn]

@@massy-3961 O(3n) is the same thing as O(n)

[@pavelpetkov8092]

hotbar = deque(hotbar) while hotbar[0] != wanted_item: hotbar.append(hotbar.popleft())

[@christophsiebert1213]

What the actual heck. And I thought ot couldn't beany worse

[@KASANITEJ]

Dont do that. Just 0th index element with sword index

[@imademedikasurya3917]

My during programing: *Pop, sort, insert, and index is not allowed make your own version...*

[@elgoogssie3969]

It can be done much better using less code using other language.

[@Anast_alma]

How do you write everything so fast?

[@theworlddiscoverer7316]

he dosent he skips the part where he types

[@Anast_alma]

@@theworlddiscoverer7316 oh ok

[@thunderskull258]

Just use remove and append

[@christophsiebert1213]

Or swap the two items directly

[@moshadoe]

I'm not too sure which would be preferred, but it seems like a dictionary would come in handy here, where you can specify the equip spots as your keys, then change the value of that key-value pairing. That way, you never really care where the item is, just that you replace the current item with the desired one, as a sort of bonus idea, check if the original value was assigned to an inventory space, and if so place it in that specific spot. If anyone knows why that's not a good idea, feel free to inform me. :)

[@thekaikage]

What extension do you use for python?

[@yungmaz13]

I assume you’re talking about the VSCode extension? If so then the extension is literally just called python

[@harisjaved1379]

Another way Hotbar[3], Hotbar[0] = Hotbar[0], Hotbar[3]

[@b001]

The list will not always be in the same order, so you won’t know the index of ‘Sword’ in the list.

[@harisjaved1379]

@@b001 yes that’s true

[@NiceO1]

quite new to Programing and i just wanted to ask if the words being typed instantly is cause you just did ctrl+v or if theres some feature i don't know about

[@production-code]

A game in python ? Hmmmm....

[@paramvirsingh5640]

Or just swap the two indices

[@lostgoat]

Good lord why

[@creeptitan]

List pops are very slow though

[@erdemisitan]

Guys I need ur help: pycharm or vscode for coding python?

[@TheBurntHoney]

I suggest pycharm. Theres an comm/edu version and with student license you get premium. Jetbrains with the new ui is pretty powerful and debugging is much easier in pycharm compared to vscode.

[@Skirmisher986]

I also would recommend pycharm, as it has a really nice integration with git

[@lucsoft]

In real code just use a map instead way simpler

[@Andrey-rc6wp]

Here's the code if you just want to swap the items instead of shifting them like in the video: hotbar[3], hotbar [0] = hotbar[0], hotbar [3]

[@championxxlNL]

This isn't necessary more efficient and I'd say becomes less readable when the program grows

[@rksmehul]

@@championxxlNL O(1) vs O(n)

[@geoafrikana]

​@@rksmehul This solution assumes that you know the index of the item which isn't the case.

[@rksmehul]

@@geoafrikana yup, didn’t think it through!

[@pramodvreddy21]

​@@geoafrikana in that case, you can use index(item) inside the index of list

[@mori7423]

That's so simple but then I think how many operations are being done on the hardware side to perform these actions. I always wonder if there's a faster way

[@electrocaruzo-karpada2485]

You could just store the item that's popped in a variable and not pop it...

[@mori7423]

@@electrocaruzo-karpada2485 true. I was also solving some quite difficult exercises using visual basic back in the day where we had to solve the exercises using as little variables as possible

[@samcousins3204]

please look into Data Structures & Algorithms!! Basic one of ur first couple classes which will answer this exact question:)

[@datboi1861]

​@@samcousins3204 This is the universe's way of getting me to finally look into DSA. Thank you, stranger.

[@samcousins3204]

@@datboi1861 Glad I could help:) i remember feeling really hopeful when i realized that coding, a hobby interest, could be supercharged with real academic thought

[@siriusblack9999]

yaaay great, and your hotbar is also shuffled so your torch moves from your hand to slot 1, your rock moves from slot 1 to slot 2, and your potion moves from slot 2 to slot 3 instead of pop/insert, you actually want want to use hotbar[0], hotbar[index] = hotbar[index], hotbar[0] to swap only the sword and torch

[@Shellll]

Ty, as a beginner I was thinking something looked weird about this solution. Much more elegant

[@afailable]

Surely an index swap would make more sense? I'm used to languages like c or c++, so it seems crazy to pop and insert on a list when you can swap references...

[@jaysonbunnell8097]

That’s likely the best solution. Python has a syntactic sugar for that case: hotbar[0], hotbar[index] = hotbar[index], hotbar[0]. Odd enough methodology from OC, but good for beginners to know those operations exist

[@Oscar-vs5yw]

I mostly work in python and I completely agree with u

[@psykozz7385]

How would you do it in C++? That's interesting to me, if you don't mind

[@SpoorloosDev]

@@psykozz7385 std::vector items{ "Hello", "World" }; std::swap(items[0], items[1]);

[@xnaaloh4437]

⁠@@psykozz7385are you talking abt the index swap? If you are then you will need a temporary variable. Like so, char* tmp = hotbar[index]; hotbar[index] = hotbar[0]; hotbar[0] = tmp;

[@IanRiley915]

Works but you should definitely swap them instead 😊

[@silentlyow]

Swap? Take a second look and you understand that simple swap won't work. But what we can both agree with that it's piece of code none of us should ever write

[@IanRiley915]

@@silentlyow You might need to elaborate further. The author is just using the 0 position of the list to represent the held item, so you can just `tmp=hotbar[0]`, `hotbar[0] = hotbar[index]`, `hotbar[index] = tmp`, which is a swap.

[@aonodensetsu]

​@@IanRiley915in python you just do hotbar[index], hotbar[0] = hotbar[0], hotbar[index] no need for a temp var

[@seriouce4832]

@@IanRiley915 your idea is simply giving a different result. apparently the task is to move sword to pos 0 and move the rest of the list behind by one (to make space for the sword). in your proposal everything stays besides torch.

[@exilednivera]

I can't remember any hotbars that shuffles items instead of just changing index of active item.

[@ABCABC-sw8mh]

it can be do easier

[@FictionHubZA]

If this was java I would have put it in an array and out a variable int in the array brackets. When a right button is pressed it increments and moves forward. When a left button is pressed it decrement and moves left.

[@MominAhmed-y6w]

Could you stop using music in your videos? It disturbs me.

[@HighTheir_]

How would you write the code to swap the items rather than push each one to the next position after popping?

[@jamesbiggs4421]

list[x], list[y] = list[y], list[x]

[@epsi]

Assuming you know the item exists in the hotbar list (i.e. you know the index method will not raise a ValueError exception): index = hotbar.index('Sword') hotbar[0], hotbar[index] = hotbar[index], hotbar[0]

[@gopallohar5534]

Which VScode theme is that?

[@Евгений-р7р3ф]

Looks like Dracula

[@unimagin2ble]

why wouldn't you just change the current item index to the index of the item they selected

[@isaacingleby8771]

This is a bad way to handle inventory, a class that can assign to .hand and remove previous items to a .inventory list would be way smoother

[@CC-1.]

You said first of all the list should be in order But Acordingly to me First of all there should be a seprate var for this and if it's undefined than the first of array!

[@sirsquirrel0]

I listed to this on repeat whilst I digested the comments. 🤷🤭

[@thegoodlifewatch]

what theme are you using?

[@retrokoh]

Index swapping would be so mucb easier. IND = hotbar.index('sword') hotbar[0], hotbar[IND] = hotbar[IND], hotbar[0]

[@xgorntv]

i will never think of making a game in python.

[@mohmaedtaoufikbaccar7567]

Result = [item, ...list.pop(item)]

[@stephystuff2955]

Do you have to repeat this code for each item to be swiped out?

[@MisterSnail1234]

Please show more memes like this one they're top🥺

[@Repulsion-kt3tx]

If javascript then first push and then shift 😮‍💨

[@smokedice]

Why are you using character quotations instead of strings? I get that python is weird, but come on!

[@drunkenfarmer2513]

All these wasted cpu cycles, its no wonder games are all laggy has shit these days

[@YuraSuper2048]

i feel like this is not an efficient way

[@Pandorarl]

Bro hasnt heard of enums

[@BHK0000]

Don’t name a variable the name of a function…

[@zataritamods7499]

This is useful information, but a terrible use case.

[@oktabramantio4709]

I've always known the .append() function but this is the first time I hear .insert() function. Guess you learn something new everyday

[@kitebeachinnbeachinn2888]

it adds to a specific position.

[@hikari1690]

Why not unshift?

[@wanderingwatcher3981]

ehm..., this is silly, just used the index itself

[@oguzhantopaloglu9442]

_list = ["a", "b", "c", "d", "e"] def swap_two_elements(_list: list[str], e1: str, e2: str): _list[_list.index(e2)], _list[_list.index(e1)] = _list[_list.index(e1)], _list[_list.index(e2)] print(_list) # [a, b, c, d, e] swap_two_elements(_list, "a", "c") swap_two_elements(_list, "d", "e") print(_list) # [c, b, a, e, d]

[@Евгений-р7р3ф]

No offense, but it's not the best way to change outer scope variables in the inner scope of a function body. Appropriate usage is returning changed objects from a function and then assign them to variables

[@andrei_camilotto]

Looks like a lot of unnecessary steps..

[@MrJonas1995]

How about switching the first one with the one you want?

[@eyebol]

why would you want to do that?

[@christophsiebert1213]

​@@eyebol In the case this wasn't sarcastic: Because that's literally what this "tip" is about. Swapping the item in the first slot with any other slot. You don't have to modify the size of the list twice to just switch two elements.

[@eyebol]

@@christophsiebert1213 i aint reading allat

[@thomasgraewe3122]

How to make ai worse:

[@JungKimrecruiter]

Good stuff!

[@tofaa3668]

terrible approach

[@maheshm1225]

Sort by des to get 4 th first

[@1010-w4d]

Or just swap with the first

[@camfunme]

You don't need either of those variables: 1) index is only used once, and doesn't exceed line usage => hotbar.pop(hotbar.index('Sword')) 2) item you already know and are using to find the index... => hotbar.insert(0, 'Sword')

[@loserguy777]

Yeah but what about parametrizing it

[@zero11010]

I'm sure all of this has been pointed out over and over. The linear pass through this isn't the end of the world. It's a small list. But, it's wasteful and easy to avoid. You can swap places, or just use a different data structure. Also, from a game mechanics perspective you usually really don't want things in a hotbar to change locations. Yeah? If you want to access your sword you would likely always want that sword to be found with button 4 (or whatever). You would want to avoid a situation where each time you change your equipped items now your inventory is potentially in a different order and you have to actually look to see what is where to equip the right item. This kinda ruins the functionality of a hotbar to begin with.

[@mattmurphy7030]

Using a different data structure is next level autism. It’s 5 items. Use a list.

[@kelvinxg6754]

Minecraft? For sure

[@DevWaddle]

what theme is that?

[@MrLazini]

This is suuuper slow

[@6644guilherme]

Very nice. Isnt there a way to get the item without removing it so i dont need to re insert it all the times? Like hotbar[0]

[@awli8861]

there is but this guy is stupid

[@algorithmic_mind]

Theme name please

[@egor.okhterov]

Use dict

[@AhmedIbrahim-fi2so]

to slow

[@hardcopy95]

Why you use index as a variable name, isn't that frowned upon

[@unimagin2ble]

easier for educational purposes

[@alessandrodestasi7811]

hotbar.insert(0, hotbar.pop(hotbar.index(“Sword”)))

[@abdelrhman..mohamed142]

❤

[@obinnaeke9663]

This is actually a great way to select the new item while maintaining the order of the list. Whe. Sword is selected, it moves to the top of the list and the order of the inventory remains the same. The swap method changes the order of the list

[@AgencyProMax]

genio

[@nigh_anxiety]

You can do a swap in a one-liner with the walrus operator: hotbar[ind], hotbar[0] = hotbar[0], hotbar[ind:=hotbar.index(item)] Of course, it should be wrapped in a Try/Except in case the target item can't be found.

[@WarOfTheTorky]

Nice list of methods I can use... I'm still learning, but I'll get there eventually.

[@rohithchirumalla]

We can use remove function and then insert so that we dont need that index part

[@hamadrehman853]

this is an excellent way to teach about array methods.

[@rysiexo]

I would go with Map, your example has too many operations.

[@Kidneydawg]

Seems like a dictionary would do what you want way more easily

[@elatedbento]

A dictionary wouldn't provide you with a sorted set of elements. At most, it would return you the elements sorted by insertion order.

[@mattmurphy7030]

A dictionary for 5 items is the stupidest thing you could have said

[@lol-kb8hz]

its incredibly inefficient to do it that way

[@seyproductions]

Cool, now my players can slice cakes with a sword.

[@xiangzhang5279]

You don't want to name any variable as "index"

[@animus8343]

Hey sir, how to change my text color like yours